The diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other disorders has long been an area of intense investigation. Non-invasive methods for examining tissue are palpation, X-ray, MRI, CT, and ultrasound imaging. When the physician suspects that a tissue may contain cancerous cells, a biopsy may be done either in an open procedure or in a percutaneous procedure. For an open procedure, a scalpel is used by the surgeon to create a large incision in the tissue in order to provide direct viewing and access to the tissue mass of interest. Removal of the entire mass (excisional biopsy) or a part of the mass (incisional biopsy) is done. For a percutaneous biopsy, a needle-like instrument is used through a very small incision to access the tissue mass of interest and to obtain a tissue sample for later examination and analysis. The advantages of the percutaneous method as compared to the open method are significant: less recovery time for the patient, less pain, less surgical time, lower cost, less risk of injury to adjacent bodily tissues such as nerves, and less disfigurement of the patient's anatomy. Use of the percutaneous method in combination with artificial imaging devices such as X-ray and ultrasound has resulted in highly reliable diagnoses and treatments.
Generally there are two ways to obtain percutaneously a portion of tissue from with the body, by aspiration or by core sampling. Aspiration of the tissue through a fine needle requires the tissue to be fragmented into small enough pieces to be withdrawn in a fluid medium. The method is less intrusive than other known sampling techniques, but one can only examine cells in the liquid (cytology) and not the cells and the structure (pathology). In core biopsy, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen or paraffin section. The type of biopsy used depends mainly on various factors present in the patient, and no single procedure is ideal for all cases. Core biopsy, however, is very useful in a number of conditions and is widely used by physicians.
A number of biopsy devices for use in combination with artificial imaging devices are known in the field. An example of a core biopsy device using an artificial imaging system is described in U.S. Pat. Nos. 4,699,154, 4,944,308, and Re. 34,056. However, these types of spring-powered devices must re-puncture the breast or organ each time a sample is taken. An example of an aspiration device using an artificial imaging system is described in the following U.S. Pat. Nos.: 5,492,130 issued to Chiou on Feb. 20, 1996; 5,526,821 issued to Jamshidi on Jun. 18, 1996; 5,429,138 issue to Jamshidi on Jul. 4, 1995; and 5,027,827 issued to Cody, et al, on Jul. 2, 1991.
Operator error can often be an issue with the above described devices. In addition there was a need for a device which could enable multiple sampling of the tissue without having to re-puncture the tissue for each sample. An example of such a product is described in U.S. Pat. No. 5,526,822 issued to Burbank, et al, on Jun. 18, 1996, which is hereby incorporated herein by reference. The Burbank et al. instrument is a type of image-guided, percutaneous, coring, breast biopsy instrument. It is vacuum-assisted, and some of the steps for retrieving the tissue samples have been automated. The physician uses this device to capture “actively” (using the vacuum) the tissue prior to severing it from the body. This allows for sampling tissues of varying hardness. The device can also be used to collect multiple samples in numerous positions about its longitudinal axis, and without needing to remove the device from the body. These features allow for substantial sampling of large lesions and complete removal of small ones. In the medical arts the instrument is commonly known as MAMMOTOME™.
Numerous improvements to the Burbank et al. device have been described in co-pending and commonly assigned U.S. application Ser. No. 08/825,899, filed on Apr. 2, 1997, the disclosure of which is hereby incorporated herein by reference. This reference describes numerous improvements to the original invention including a molded tissue cassette housing which permits the handling and viewing of multiple tissue samples without physical contact by the instrument operator. Another improvement to the original device includes the interconnection of the housing to the piercing needle by a thumbwheel which permits the needle to rotate relative to the housing, thereby preventing the vacuum tube from wrapping about the housing.
Other improvements to the above described device are disclosed in U.S. Pat. No. 6,007,497 issued to Huitema on Dec. 28, 1999, which is hereby incorporated herein by reference. This reference described improvements to the fluid management capabilities of the system, resulting in part from the addition of sealing elements located in critical areas of the biopsy probe.
In actual clinical use for breast biopsy, the MAMMOTOME instrument (probe and driver assembly) is mounted to the three axis positioning head of an x-ray imaging machine. The three axis positioning head is located in the area between the x-ray source and the image plate. The x-ray machines are outfitted with a computerized system which requires two x-ray images of the breast be taken with the x-ray source at two different positions in order for the computer to calculate the x, y and z axis location of the suspect abnormality. In order to take the stereo x-ray images the x-ray source must be conveniently movable. The x-ray source therefore is typically mounted to an arm which, at the end opposite the x-ray source, is pivotally mounted to the frame of the machine in the region of the image plate.
To image the breast, the breast is placed between the x-ray source and the image plate, the breast being placed on the image plate. In order to take the necessary stereo images the clinician will manually position the x-ray source to one side and then the other of the center axis of the machine (typically 15-20 degrees to each side of the center axis), obtaining an x-ray image on each side of the breast. The computer will then, with great accuracy, calculate the precise x, y and z location of the suspect abnormality in the breast and automatically communicate to the clinician or directly to the positioning head the targeting coordinates for the biopsy device. The clinician can then manually, or automatically, position the biopsy probe into the breast at the precise location of the abnormality.
There are generally two styles of x-ray machines in wide spread use for breast imaging. One style is known as “prone”, because the patient lies face down during the x-ray and biopsy procedures on a table that is configured horizontal to the floor. The other style, in more wide spread use, is the “upright”. The center axis of the upright imaging machine is configured vertical to the floor and the patient sits in front of the machine during the x-ray and biopsy procedures.
The above described biopsy instruments mount to a three axis positioning head located between the x-ray source and image plate on the breast x-ray imaging machine. The distance between the x-ray source and imaging plate is known in the industry as the SID (Source to Image Distance). There is no standard SID in the industry and in fact the SID varies greatly from one x-ray machine manufacturer to another.
This creates a problem for the manufacturers of devices, like the MAMMOTOME, which is intended to be mounted between the x-ray source and image plate of the x-ray imaging machine. In the case of the MAMMOTOME instrument with its length from the distal tip of the biopsy probe to the most proximal portion of the driver measuring approximately 41 centimeters, adequate mounting space has been found to exist on the prone style x-ray machines. However, on some of the more popular upright style x-ray imaging machines the SID has been found to be as little as 29 centimeters, obviously too small in which to mount the MAMMOTOME. What is needed, therefore, is a biopsy instrument configured to permit mounting on the shorter SID x-ray imaging machines.